Od PET lahví k dobrotám

The treatment of waste PET bottles has become a pressing global issue over the last few decades, and many scientific teams are currently working on solutions to it. There are many different approaches of how to solve this problem. The present article outlines the possibility to process terephthalic acid, which is the hydrolysis product of polyethylene terephthalate, into vanillin, a compound widely used in the food industry. The work of British scientists who have succeeded in using genetic modification to produce a strain of E. coli RARE_pVanX capable of processing polyethylene terephthalate hydrolysates to the desired vanillin is presented in a broader context.

Using Granulate Composites with Calcined Phosphogypsum and Pet Additive in Asphalting

The paper discusses the change of phosphogypsum surface state produced by Apatit (Cherepovetsky branch, Vologda region) during calcination at 298-1173 K. The authors have determined the average size of its crystallites and studied the atomic composition of raw materials and finished composites that include crushed rock fraction (5-10 mm), oil bitumen, and polyethylene terephthalate additive (1.0-1.2 wt. %). The compounds present in calcined phosphogypsum have been analyzed by X-ray diffraction. The granulate was obtained by pelletizing phosphogypsum with a mixture of the above components. The paper presents the assessment of its physical and chemical properties. The granulated composites based on the specified samples of calcined phosphogypsum, bitumen, and melted polyethylene terephthalate waste show great promise for construction road works in European countries in summer and winter, as well as countries with tropical climates.

Structural insights into dihydroxylation of terephthalate, a product of polyethylene terephthalate degradation

Biodegradation of terephthalate (TPA) is a highly desired catabolic process for the bacterial utilization of this Polyethylene terephthalate (PET) depolymerization product, but to date, the structure of terephthalate dioxygenase (TPDO), a Rieske oxygenase (RO) that catalyzes the dihydroxylation of TPA to a cis -diol is unavailable. In this study, we characterized the steady-state kinetics and first crystal structure of TPDO from Comamonas testosteroni KF1 (TPDO KF1 ). The TPDO KF1 exhibited the substrate specificity for TPA ( k cat / K m = 57 ± 9 mM −1 s −1 ). The TPDO KF1 structure harbors characteristics RO features as well as a unique catalytic domain that rationalizes the enzyme’s function. The docking and mutagenesis studies reveal that its substrate specificity to TPA is mediated by Arg309 and Arg390 residues, two residues positioned on opposite faces of the active site. Additionally, residue Gln300 is also proven to be crucial for the activity, its substitution to alanine decreases the activity ( k cat ) by 80%. Together, this study delineates the structural features that dictate the substrate recognition and specificity of TPDO. Importance The global plastic pollution has become the most pressing environmental issue. Recent studies on enzymes depolymerizing polyethylene terephthalate plastic into terephthalate (TPA) show some potential in tackling this. Microbial utilization of this released product, TPA is an emerging and promising strategy for waste-to-value creation. Research from the last decade has discovered terephthalate dioxygenase (TPDO), as being responsible for initiating the enzymatic degradation of TPA in a few Gram-negative and Gram-positive bacteria. Here, we have determined the crystal structure of TPDO from Comamonas testosteroni KF1 and revealed that it possesses a unique catalytic domain featuring two basic residues in the active site to recognize TPA. Biochemical and mutagenesis studies demonstrated the crucial residues responsible for the substrate specificity of this enzyme.